Functional Applications of Polyarginine-Hyaluronic Acid-Based Electrostatic Complexes.

Background: Electrostatic complexes of poly (l-Arginine) (pArg) and hyaluronic acid (HA) have been investigated for their functional applications to supply free or polymeric form of l-Arginine (Arg) to target cells. As a vital amino acid, Arg plays significant role in multitude of pathophysiological processes ranging from wound healing to cancer. However, serum arginase expression and toxicity of Arg at cellular level renders exogenous delivery of this amino acid a challenging task. We showed that polyarginine-hyaluronic acid ionic nanocomplexes (pArg-HA iNCs) could be an effective way to deliver Arg to target cell populations. Materials and Methods: These electrostatic complexes were prepared by mixing HA (average m.w. of 200 kDa) with pArg (m.w. 5-15 kDa; Sigma) in aqueous solutions and purifying over glycerol. Nanocomplexes were characterized for their particle size, surface charge, capacity to release l-Arg, and intracellular uptake of complexes. Results: Synthesized nanocomplexes showed hydrodynamic diameter ranging from 140-306 nm depending on the content of pArg or HA within the formulation. With surface charge (ζ-potential) of -29 mV, the nanocomplexes showed pH-dependent release of Arg. At pH 7.4, pArg-HA iNCs released 30% of the total Arg-content, while at pH 5.0, 60% of Arg was released after 24 h. These electrostatically stabilized complexes were found to promote growth of human dermal fibroblasts (HDF) in wound-healing assay and increased nitric oxide (NO) activity in these cells in a time-dependent manner. Nanocomplexes also showed cellular uptake and enhanced dose-dependent toxicity against two pancreatic cancer cell lines, i.e. MIA PaCa-2 and Panc-1. Interestingly, the cytotoxic effect was synergized upon pre-treatment of the cells with a frontline chemotherapeutic agent, gemcitabine (GEM), and was not observed when the cells were treated with Arg alone. Conclusion: As such, this communication shows the prospect of pArg-HA iNC electrostatic nanocomplexes to interact and interfere with intracellular Arg metabolic machinery conducive to rescuing different pathological conditions.

Electrospun nanofibers in cancer research: from engineering of in vitro 3D cancer models to therapy.

Electrospinning is historically related to tissue engineering due to its ability to produce nano-/microscale fibrous materials with mechanical and functional properties that are extremely similar to those of the extracellular matrix of living tissues. The general interest in electrospun fibrous matrices has recently expanded to cancer research both as scaffolds for in vitro cancer modelling and as patches for in vivo therapeutic delivery. In this review, we examine electrospinning by providing a brief description of the process and overview of most materials used in this process, discussing the effect of changing the process parameters on fiber conformations and assemblies. Then, we describe two different applications of electrospinning in service of cancer research: firstly, as three-dimensional (3D) fibrous materials for generating in vitro pre-clinical cancer models; and secondly, as patches encapsulating anticancer agents for in vivo delivery.

Cell deformation and acquired drug resistance: elucidating the major influence of drug-nanocarrier delivery systems.

Cancer diagnosis and its stage-wise assessment are determined through invasive solid tissue biopsies. Conversely, cancer imaging is enriched through emission tomography and longitudinal high-resolution analysis for the early detection of cancer through altered cell morphology and cell-deformation. Similarly, in post multiple chemo-cycle exposures, the tumor regression and progression thereafter are not well understood. Here, we report chemo-cycles of doxorubicin (Dox) carrying nanoparticles (NPs) to be highly indicative of cell deformation and a progressive indicator of phenotypic expressions of acquired drug resistance (ADR). We designed graphene (G) based nanocarriers by chemically conjugating multiple components: (i) G; (ii) iron oxide (Fe3O4) NPs; and (iii) Dox through a cysteine (Cys) linker (G-Dox and G-Cys-Fe3O4-Dox). Although Dox underwent cell diffusion, the G-based nanocarriers followed a receptor-mediated endocytosis which created a profound impact on the cell membrane integrity. ADR owing to Dox and G-based nanocarriers was analyzed through a cytotoxicity assay, cell morphology deformation parameters and cellular uptake kinetic patterns. Interestingly, after the third chemo-cycle, G-Dox incubated cells showed the greatest decrease in the alteration of the nuclear surface area (NSA) of ∼28%, a ∼40% reduction of the cell surface area (CSA) and a ∼32% increase in the cell roundness (CRd). Our results suggested that the G-based nanocarriers induced the cell deformation process, subsequently resulting in ADR. Although the G-based nanocarriers initiated ADR, G-Dox was most cytotoxic to cancer cells and induced the maximum cell morphology deformation within our scope of study. This outcome implies caution is needed when using G-based nanocarriers and other multi-component nanosystems for Dox delivery as they lead to possible phenotypic expressions of drug resistance in cancer cells.

Cellular regeneration and proliferation on polymeric 3D inverse-space substrates and the effect of doxorubicin.

Spatial arrangement for cells and the opportunity thereof have implications in cell regeneration and cell proliferation. 3D inverse space (3DIS) substrates with micron-sized pores are fabricated under controlled environmental conditions from polymers such as poly(lactic-co-glycolic) acid (PLGA), poly(lactic acid) (PLA) and poly(styrene) (PS). The characterization of 3DIS substrates by optical microscopy, scanning probe microscopy (SPM), etc. shows pores within 1-18 µm diameter and prominent surface roughness extending up to 3.9 nm in height over its base. Conversely, to compare two-dimensional (2D) versus 3DIS substrates, the crucial variables of cell height, cell spreading area and cell volume are compared using lung adenocarcinoma (A549) cells. The results indicate an average cell thickness of ∼6 µm on a glass substrate whereas cells on PLGA 3DIS were ∼12 µm in height, occasionally reaching 20 µm, with a 40% decreased cell spreading area. A549 cells cultured on polymer 3DIS substrates show a cell regeneration growth pattern, dependent on the available spatial volume. Furthermore, PLGA 3DIS cell culture systems with and without graded doxorubicin (DOX) pre-treatment result in potent cell inhibition and cell proliferation, respectively. Additionally, standard DOX administration to A549 cells in the PLGA 3DIS system revealed altered drug sensitivity. 3DIS demonstrates utility in facilitating cellular regeneration and mimicking cell proliferation in defined spatial arrangements.